Medicarpin derivatives and analogs

ABSTRACT

Medicarpin derivatives and related pharmaceutical compositions and methods of treatment are disclosed. The compounds are useful as inhibitors of mammalian leukotriene biosynthesis. As such, they are useful therapeutic agents for treating allergic conditions, asthma, cardiovascular disorders and inflammation.

BACKGROUND OF THE INVENTION

This invention involves certain medicarpin derivatives. These compoundsare useful inhibitors of mammalian leukotriene biosynthesis. As such,they are useful therapeutic agents for treating allergic conditions,asthma, cardiovascular disorders and inflammation.

The leukotrienes are a novel group of biologically active mediatorsderived from arachidonic acid through the action of lipoxygenase enzymesystems. There are two groups of leukotrienes derived from the unstableLeukotriene A₄. The first of these are the peptido-lipid leukotrienes,the most important being Leukotrienes C₄ and D₄. These compoundscollectively account for the biologically active material known as theslow reacting substance of anaphylaxis. The leukotrienes are potentsmooth muscle contracting agents, particularly on respiratory smoothmuscle but also on other tissues (e.g. gall bladder). In addition, theypromote mucous production, modulate vascular permeability changes andare potent inflammatory agents in human skin. The most importantcompound in the second group of leukotrienes is Leukotriene B₄, adihydroxy fatty acid. This compound is a potent chemotactic agent forneutrophils and eosinophils and in addition, may modulate a number ofother functions of these cells. It also effects other cell types such aslymphocytes and for example may modulate the action of T-suppressorcells and natural killer cells. When injected in vivo, in addition topromoting the accumulation of leukocytes, Leukotriene B₄ is also apotent hyperalgesic agent and can modulate vascular permeability changesthrough a neutrophil dependent mechanism. Both groups of leukotrienesare formed following oxygenation of arachidonic acid through the actionof a 5-lipoxygenase enzyme. See for example, D. M. Bailey et al., Ann.Rpts. Med. Chem. 17 203 (1982).

RESPIRATORY CONDITIONS

(a) Asthma

The leukotrienes are potent spasmogens of human trachea, bronchus andlung parenchymal strips, and when administered to normal volunteers asaerosols are 3,800 times more potent than histamine at inducing a 50%decrease in air flow at 30% of vital capacity. They mediate increases invascular permeability in animals and promote mucous production in humanbronchial explants. In addition, Leukotriene B₄ may also mediate mucousproduction and could be an important mediator of neutrophil andeosinophil accumulation in asthmatic lungs. 5-Lipoxygenase products arealso thought to be regulators of mast cell degranulation and recentstudies with human lung mast cells have suggested that 5-Lipoxygenaseinhibitors, but not corticosteroids, may suppress antigen-induced mastcell degranulation. In vitro studies have shown that antigen challengeof human lung results in the release of leukotrienes and in additionpurified human mast cells can produce substantial amounts ofleukotrienes. There is therefore good evidence that the leukotrienes areimportant mediators of human asthma. 5-Lipoxygenase inhibitors wouldtherefore be a new class of drugs for the treatment of asthma. See forexample, B. Samuelson, Science 220 568-575 (1983).

SKIN DISEASES

(a) Psoriasis

Psoriasis is a human skin disease which effects between two and sixpercent of the population. There is no adequate therapy for psoriasisand related skin conditions. The evidence for leukotriene involvement inthese diseases is as follows. One of the earliest events in thedevelopment of prepapillary lesions is the recruitment of leukocytes tothe skin site. Injection of Leukotriene B₄ into human skin results in apronounced neutrophil accumulation. There are gross abnormalities inarachidonic acid metabolism in human psoriatic skin. In particular,highly elevated levels of free arachidonic acid can be measured as wellas large amounts of lipoxygenase products. Leukotriene B₄ has beendetected in psoriatic lesions, but not in uninvolved skin, inbiologically significant amounts.

ALLERGIC CONDITIONS

(a) Leukotrienes can be measured in nasal washings from patients withallergic rhinitis and are greatly elevated following antigen challenge.Leukotrienes may mediate this disease through their ability to regulatemast cell degranulation, by modulating mucous production and mucocillaryclearance and by mediating the accumulation of inflammatory leukocytes.

Leukotrienes can also mediate other diseases. These include atopicdermatitis, gouty arthritis and gall bladder spasms. In addition, theymay have a role in cardiovascular disease because leukotrienes C₄ and D₄act as coronary and cerebral arterial vasoconstrictors, and thesecompounds may also have negative inotropic effects on the myocardium. Inaddition, the leukotrienes are important mediators of inflammatorydiseases through their ability to modulate leukocyte and lymphocytefunction.

A number of medicarpin derivatives of the general Formula below areknown: ##STR1## for example, medicarpin was described in Plant Path. 1:41, 1971; Phytopath., 58: 1377, 1968; 62: 1365, 1975 and 13: 291, 1974.It was isolated from Dalbergia Odorifera T. Chen. and showed negativeresults when tested for prostaglandin inhibition. However, none of thesereferences discloses medicarpin or its analogs as inhibitors ofmammalian leukotriene biosynthesis, nor does any one of these referencesteach that these compounds are useful for the treatment of asthma,allergies, inflammation and certain skin diseases.

SUMMARY OF THE INVENTION

This invention is directed to pharmaceutical compositions containing acompound of the Formula I: ##STR2## or a pharmaceutically acceptablesalt thereof, a method of treatment using the composition and certainnovel compounds of formula I.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of the present invention is a pharmaceutical compositioncontaining a compound of the Formula I: ##STR3## wherein R¹ and R²independently are

(1) hydrogen; or

(2) alkyl having 1-6 carbon atoms.

The preferred compounds of Formula I are those wherein when R¹ is H, R²is CH₃ and vice versa.

The compounds of the Formula I have unexpected activity as inhibitors ofthe mammalian biosynthesis of leukotrienes. The compounds of Formula Itherefore are expected to act as inhibitors of the mammalian5-Lipoxygenase enzyme system of the arachidonic acid cascade. Thisinhibition of the mammalian biosynthesis of leukotrienes indicates thatthe compositions would be useful to treat, prevent or ameliorate, inmammals and especially in humans (1) pulmonary conditions includingdiseases such as asthma, (2) allergies and allergic reactions such asallergic rhinitis, contact dermatitis, allergic conjunctivitis and thelike, (3) inflammation such as arthritides, (4) pain, (5) skinconditions such as psoriasis and the like and (5) cardiovascularconditions such as angina and the like.

Representative compounds of Formula I have been tested using thefollowing assay to determine their mammalian leukotriene biosynthesisinhibiting activity and other relevant activities:

CXBG cells grown intraperitoneally in CB₄ B₆ /F₁ /J mice were washed 5times in Dulbeccos phosphate buffered saline without calcium ormagnesium, suspended in medium 199 (Gibco) at 2×10⁶ cells/ml, andincubated 15 minutes at 37°. Inhibitor solutions in methanol wereincubated with the cells (10 μl/600 μl cells), for 5 minutes at 37°, andthe cells were stimulated with 60 μl A23187 (50 μg/ml) for 10 minutes at37°. Aliquots were removed for measurement of leukotriene C₄ orthromboxane B₂ by enzyme immunoassay as previously reported (D. K.Miller, et al., J. Immunological Methods, 81, 169-185, 1985). Thepercentage inhibition was calculated by the following: ##EQU1##

IC₅₀ s were determined graphically.

                  TABLE I                                                         ______________________________________                                        Assay Results                                                                 Inhibition of CXBG leukotriene and prostoglandin                              production by (Iso)medicarpin                                                 Eicosanoid    IC.sub.50 (mg/ml)                                               ______________________________________                                        LTC.sub.4      0.1 μg/ml                                                   TXB.sub.2     >5 μg/ml                                                     ______________________________________                                    

The test results presented above show that representative compounds ofFormula I inhibit the mammalian biosynthesis of leukotrienes and haverepresentative pharmaceutical utility e.g., for asthma, pain andallergy.

The pharmaceutical compositions of the present invention will containsufficient compound of Formula I in a dosage form suitable forinhibiting the mammalian biosynthesis of leukotrienes or, for thetreatment desired. The effective concentration of the Formula I compoundin the composition will vary as required by the mode of administration,dosage form and pharmacological effect and level desired. A generaldaily dosage of Formula I will range from about 10 μg to 100 mg/kg ofbody weight. This dosage may be administered in single or dividedindividual doses. More or less of the general daily dosage may benecessary depending upon the individual needs of the patient.

For treating pulmonary conditions such as asthma, the mode ofadministration may be oral, parenteral, by inhalation, by suppositoryand the like. Suitable oral dosage forms are tablets, elixirs,emulsions, solutions, capsules, including delayed or sustained releasecapsules and the like. Parenteral dosage forms include solutions,emulsions and the like. Dosage forms for administration by inhalationincluding sprays, aerosols and the like. These inhalation formulationsmay be administered in metered doses ranging from about 0.1 μg to about200 μg, administered as needed.

For treating allergies or allergic reactions, such as allergicconjunctivitis, allergic rhinitis and the like, the Formula I compoundmay be administered by any conventional mode, e.g., orally,parenterally, topically, subcutaneously, by inhalation and the like. Theoral and parenteral dosage forms are the same type as for the pulmonarytreatment. The topical application dosage forms include ointments,salves, controlled release patches, emulsions, solutions, thixotropicformulations, powders, sprays and the like. For topical application, thepercent by weight active ingredient (Formula I compound) may vary fromabout 0.001 to about 10%.

For treating inflammation the mode of administration may be oral,parenteral, by suppository and the like. The various dosage forms arethe same as those described above.

For treating skin diseases such as psoriasis, atopic dermatitis and thelike, oral, topical or parenteral administration is useful. For topicalapplication to the diseased area salves, patches, controlled releasepatches, emulsions, etc., are convenient dosage forms.

For use as an analgesic, i.e., for treating pain, any suitable mode ofadministration may be used, e.g., oral, parenteral, by insufflation, bysuppository and the like.

For treating cardiovascular conditions such as angina pectoris, etc.,any suitable mode of administration, e.g. oral, parenteral, topical,insufflation, etc. and dosage form e.g. pills, liquid formulations,controlled release capsules, controlled release skin patches, etc. maybe used.

In addition to the common dosage forms set out above, the compound ofFormula I may also be administered for the various utilities andindications or for inhibiting leukotriene synthesis by controlledrelease means and/or delivery devices such as those described in U.S.Pat. Nos. 3,845,770; 3,916,899; 3,536,809; 3,598,123; 3,630,200 and4,008,719.

Dosage forms for application to treat the eye are also disclosed in U.S.Pat. No. 4,348,398.

In preparing suitable dosage forms, conventional compounding proceduresand ingredients e.g. diluents, carriers, etc. may be used. The followingare examples of representative pharmaceutical dosage forms:

    ______________________________________                                        Injectible Suspension                                                                              mg/mL                                                    ______________________________________                                        Compound of Formula I                                                                              1-100                                                    Methylcellulose      5.0                                                      Tween 80             0.5                                                      Benzyl alcohol       9.0                                                      Methyl paraben       1.8                                                      Propyl paraben       0.2                                                      Water for injection to a total volume                                         of 1 ml                                                                       ______________________________________                                        Aerosol for Oral Inhibition                                                                        mg/can (200 doses/can)                                   ______________________________________                                        Compound of Formula I                                                                              2-40                                                     Oleic Acid           0.2-4.0                                                  Trichloromonofluoro methane                                                                        5,000-8,000 To a total                                   Dichloromonofluoro methane                                                                         15,000-12,400 of 20,400                                  ______________________________________                                        Cream                mg/g                                                     ______________________________________                                        Compound of Formula I                                                                              1-100                                                    Cetyl alcohol        130.0                                                    Sodium Lauryl Sulfate                                                                              15.0                                                     Propylene Glycol     100.0                                                    Methyl paraben       1.8                                                      Propyl paraben       1.2                                                      Purified Water of sufficient quantity to                                      make total 1 g                                                                ______________________________________                                        Ointment             mg/g                                                     ______________________________________                                        Compound of Formula I                                                                              1-100                                                    Methyl paraben       1.8                                                      Propyl paraben       1.2                                                      Petrolatum of sufficient quantity to                                          make total 1 g                                                                ______________________________________                                        Tablet               mg/table                                                 ______________________________________                                        Compound of Formula I                                                                              0.2-350                                                  Microcrystalline Cellulose                                                                         0-349.8                                                  Providone            14.0                                                     Microcrystalline Cellulose                                                                         90.0                                                     Pregelatinized Starch                                                                              43.5                                                     Magnesium Stearate   2.5                                                                           500                                                      ______________________________________                                        Capsule              mg/capsule                                               ______________________________________                                        Compound of Formula I                                                                              0.2-350                                                  Lactose Powder       248.5-598.3                                              Magnesium Stearate   1.5                                                                           600                                                      ______________________________________                                    

Examples showing the isolation and purification of the compounds of thisinvention are described below. These examples are provided merely as anaid to understand the instant invention. No limitation is intended,other than those that appear in the appended claims. All temperaturesare in degrees Celsius and are uncorrected.

ISOLATION OF (ISO)MEDICARPIN

The dried chloroform extract of Dalbergiae Odoriferae comprisingapproximately 1.5 gm of viscous material was triturated with 8 mlmethanol and centrifuged.

The supernatent was charged to a 1 inch I.D. by 2.2 meter long columnfilled with Sephadex LH-20 in methanol. The column was eluted at about25° C. (temperature may range from room temperature to 50°) withmethanol and CXBG active fractions eluting between 1.35 and 1.50 columnvolumes were concentrated yielding 116 mg of residue. Twenty-five mg ofthis residue was further fractionated by preparative reverse phase HPLCusing a gradient from 30% to 100% acetonitrile at 40° C. (temperaturemay range from room temperature to 50° C.). The CXBG active fractionswere combined yielding 14 mg of essentially pure (iso)medicarpin asdetermined by isocratic analytical HPLC., U.V., nmr and massspectroscopy spectra.

What is claimed is:
 1. A method of treating or preventingleukotriene-induced diseases which comprises administering to a patientin need of such treatment an effective amount of a Compound of formulaI; ##STR4## wherein: R₁ and R₂ independently are:(1) hydrogen; or (2)alkyl having 1-6 carbon atoms.
 2. The method of claim 1 wherein theactive compound is medicarpin or isomedicarpin.